Extension-clamp.



L. HOFFMAN.

EXTENSION CLAMP.

APPLICATION FILED Jmze. l9l6- Patented Sept. 25, 1917.

WITNESSES; o yz%da 571/ drawings, in which EXTENSION-CLAMP.

Specification of Letters Patent.

Patented Sept. 25, 1917.

Application filed January 26, 1916. Serial No. 74,352.

To all whom it may concern:

Be it known that I, LOUIS HOFFMAN, a subject of the Czar of Russia, residing at the city and county of San Francisco and State of California, have invented new and useful Improvements in Extension-Clamps, of which the following is a specification.

This invention relates to improvements in clamps such as are used to hold parts together for further manipulation, and particularly for the use of carpenters, cabinet makers, and like artisans.

The invention consists in the employment of telescopic concentric tubes, one slotted to move inside the other to provide the necessary extension and for the fitting and movement of clamping jaws and the pawls by which the jaws are retained in locking position.

It also comprises mechanism and details of construction which will be more fully described by reference to the accompanying Figure l is a side elevation of the clamp.

Fig. 2 is a transverse section on line 2-2 of Fig. 1.

Fig. 3 is a transverse section on line 3-3 of Fig. 1.

Fig. 4.- is a partial section showing device to lock the members together.

As shown in the drawings, A and B are the two extension members, one of which is slidable longitudinally within and guided in its movements by the other. .These members are here shown as tubular for lightness and providing suflicient rigidity. The outer member or body A is slotted along the top and the inner member or extensible part B has fixed to it a lug 2 which projects up through the slot and has fulcrumed to it a pawl 3, one end of which is adapted to engage notches 4 upon the outer member A, and this pawl is held in engagement by a spring 5 acting against the opposite end of the pawl. The outer end of the member B has fixed to it an extension A, slotted, and

corresponding in size with the outer member A.

6 is a sliding jaw, movableupon the member AA' and provided with a pawl 7 which is adapted to engage with coacting teeth 4 upon the said member. 8 is an inner jaw member having clasping arms adapted to engage and hold it slidably upon the member A.

A nut 9 is fixed to the inner end of the member A and a screw 10 is movable through this nut, by turning a crank or hand-wheel l1 fixed upon the screw shank, so as to advance the end of the screw into contact with the back of the clamp 8 and advance it to produce the desired clamping force against the article to be clamped. The opposite side of the article will be compressed by the opposing clamp 6 which will be held in position by the pawl 7 holding the clamping jaw 6 in place. An inwardly projecting tongue 6 may enter the slot in the outer tubular member to prevent the sliding jaw. 6 from turning with relation thereto.

When small articles are to be clamped the lug 2, to which it is attached and which is fixed to the inner member, to be extended to any desired extent, and the jaw 6 is moved out upon the extension portion A. When the desired extension has been reached, the pawl 8 is dropped into engagement with a notch 4 and this retains the extension in place. The outer clamping jaw being held by its pawl, the inner jaw may be advanced by the screw to firmly compress the article to be held. The concentric tubular extension members make for lightness and rigidity.

Various changes may be made in the apparatus herein claimed without departing from the essence of the invention.

A spring catch 12, located contiguous to the pawl, will engage a notch 13 in the outer tube to prevent the inner one from being entirely drawn out, but if it is necessary to separate the tubes the spring 12 may be depressed and disengaged. A screw 14 in the outer member A serves to prevent the clamp 6 from falling off, if the pawl should be released.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is

1. An adjustable clamp comprising a slotted, tubular outer member having a movable clamp jaw, means to advance or retract the jaw, a tubular inner member slidable within the first member and having an enlargement at its outer end of the same diameter as the outer member, an opposed clamp jaw having a spring-pressed latch and engageable with and slidable upon the outer tubular member and the enlargement, a lug projecting from the inner end of the inner member through'the slot in the outer member, a latch carried by the lug, said outer member having notches upon the edges of the slot with which the said last named latch may engage to retain the inner member in position and also to engage said first mentioned latch and lock the opposing clamp jaw to the inner or the outer member.

2. In an extension clamp of the character described, an outer tubular slotted member and an inner telescopically slidable member, a jaw on the outer member, means borne by the outer member. to actuate said jaw, an opposed jaw upon the outer end of the inner slidable member, a notched bearing upon the outer end of the inner member registering with the end of the outer member to allow the clamp to be moved from one member to the other, a spring-pressed latch carried by the inner end of the inner member, and a spring-pressed latch carried by said opposed jaw, said outer member having notches with which each of said latches are engageable.

In testimony whereof I have hereunto set I my hand in the presence of two subscribing witnesses.

LOUIS HOFFMAN.

Witnesses:

JOHN H. HERRING, LEONARD J. F ORDE. 

